Establishment of a variant type of turkey herpesvirus which releases cell-free virus into the culture medium in large quantities. Brief report.

A variant turkey herpesvirus (HVT/VT) which releases 10(5.0) plaque-forming units per 0.1 ml of cell-free virus into the culture medium was established from the prototype HVT FC 126 strain (HVT/WT). Many enveloped and naked virions of HVT/VT but only naked virions of HVT/WT were found in the culture medium. By the HindIII restriction cleavage patterns, the HVT/VT DNAs were almost identical to those of HVT/WT. The HVT/VT was replication-defective in chickens.